U.S. patent number 11,315,509 [Application Number 17/277,729] was granted by the patent office on 2022-04-26 for driving method for liquid crystal display device.
This patent grant is currently assigned to INFOVISION OPTOELECTRONICS (KUNSHAN) CO., LTD.. The grantee listed for this patent is INFOVISION OPTOELECTRONICS (KUNSHAN) CO., LTD.. Invention is credited to Te-Chen Chung, Chia-Te Liao, Yanbing Qiao, Xiaoneng Yan.
United States Patent |
11,315,509 |
Qiao , et al. |
April 26, 2022 |
Driving method for liquid crystal display device
Abstract
A driving method for a liquid crystal display device is
provided. The liquid crystal display device has a wide viewing
angle mode and a narrow viewing angle mode. The driving method
includes: in the wide viewing angle mode, all the frames of the
liquid crystal display device have the same display brightness; in
the narrow viewing angle mode, the odd frames and the even frames
of the liquid crystal display device have different display
brightness. In the narrow viewing angle mode of the liquid crystal
display device, by using an alternate driving method of bright
frames and dark frames, the mura degree is significantly reduced,
and the smoothness of dynamic picture display is improved, thereby
improving the use experience of users.
Inventors: |
Qiao; Yanbing (Suzhou,
CN), Yan; Xiaoneng (Suzhou, CN), Chung;
Te-Chen (Suzhou, CN), Liao; Chia-Te (Suzhou,
CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
INFOVISION OPTOELECTRONICS (KUNSHAN) CO., LTD. |
Suzhou |
N/A |
CN |
|
|
Assignee: |
INFOVISION OPTOELECTRONICS
(KUNSHAN) CO., LTD. (Suzhou, CN)
|
Family
ID: |
1000006267594 |
Appl.
No.: |
17/277,729 |
Filed: |
November 5, 2018 |
PCT
Filed: |
November 05, 2018 |
PCT No.: |
PCT/CN2018/114023 |
371(c)(1),(2),(4) Date: |
March 18, 2021 |
PCT
Pub. No.: |
WO2020/093216 |
PCT
Pub. Date: |
May 14, 2020 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20210350757 A1 |
Nov 11, 2021 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G09G
3/3614 (20130101); G09G 3/3648 (20130101); G09G
2320/068 (20130101); G09G 2320/028 (20130101); G09G
2320/0673 (20130101); G09G 2320/0233 (20130101) |
Current International
Class: |
G09G
3/36 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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107991800 |
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3999081 |
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I589957 |
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Jul 2017 |
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TW |
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201805705 |
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Feb 2018 |
|
TW |
|
Primary Examiner: Jansen, II; Michael J
Attorney, Agent or Firm: Chiang; Cheng-Ju
Claims
What is claimed is:
1. A driving method for a liquid crystal display device having a
wide viewing angle mode and a narrow viewing angle mode, wherein
the liquid crystal display device comprises a first substrate, a
second substrate disposed opposite to the first substrate, and a
liquid crystal layer located between the first substrate and the
second substrate, an auxiliary electrode is provided on the first
substrate, a common electrode and pixel electrodes are provided on
the second substrate; wherein the driving method comprises: when a
DC reference voltage is applied to one of the common electrode and
the auxiliary electrode, and the voltage applied to the other one
of the common electrode and the auxiliary electrode is same or
similar as the common electrode, the voltage difference between the
common electrode and the auxiliary electrode is less than a preset
value, the liquid crystal display device is in the wide viewing
angle mode; and in the wide viewing angle mode, when displaying
static images, all frames of the liquid crystal display device have
the same display brightness; when a DC reference voltage is applied
to one of the common electrode and the auxiliary electrode, and an
AC voltage fluctuated up and down around the DC reference voltage
is applied to the other one of the common electrode and the
auxiliary electrode, the voltage difference between the common
electrode and the auxiliary electrode is greater than a preset
value, the liquid crystal display device is in the narrow viewing
angle mode; and in the narrow viewing angle mode, odd frames and
even frames of the liquid crystal display device have different
display brightness.
2. The driving method according to claim 1, wherein in the narrow
viewing angle mode, the display brightness of the odd frames of the
liquid crystal display device is higher than that of the even
frames, or the display brightness of the even frames of the liquid
crystal display device is higher than that of the odd frames.
3. The driving method according to claim 2, wherein in the narrow
viewing angle mode, the liquid crystal display device adopts a way
of varying the driving voltages to realize that the odd frames and
the even frames have different display brightness.
4. The driving method according to claim 3, wherein in the narrow
viewing angle mode, the liquid crystal display device is driven
with two sets of gamma voltages of different voltage values, one
set of gamma voltages is used when the odd frames are displayed,
and the other set of gamma voltages is used when the even frames
are displayed.
5. The driving method according to claim 2, wherein in the narrow
viewing angle mode, the liquid crystal display device adopts a way
of processing image data to realize that the odd frames and the
even frames have different display brightness.
6. The driving method according to claim 5, wherein the liquid
crystal display device comprises an image processor, the image
processor is used to add or subtract the image data, and the
processed image data is then transmitted to the liquid crystal
display device for display.
7. The driving method according to claim 1, wherein the AC voltage
changes its polarity once every two frames, and the period of the
AC voltage is four times the display time of each frame of the
liquid crystal display device.
8. The driving method according to claim 1, wherein the AC voltage
changes its polarity twice per frame, and the period of the AC
voltage is equal to the display time of each frame of the liquid
crystal display device.
9. The driving method according to claim 1, wherein in the narrow
viewing angle mode, the image refresh rate of the liquid crystal
display device is 120 frames per second.
10. The driving method according to claim 1, wherein the liquid
crystal display device is provided with a viewing angle switching
button configured for users to switch different viewing angle modes
of the liquid crystal display device.
11. The driving method according to claim 1, wherein the liquid
crystal display device detects by a detection sensor whether there
is a person near the liquid crystal display device, and the liquid
crystal display device is controlled to automatically switch
between different viewing angle modes according to the detection
result.
12. The driving method according to claim 1, wherein the liquid
crystal display device detects the usage scenarios of users, and
the liquid crystal display device is controlled to automatically
switch between different viewing angle modes according to the
detection result.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a 35 U.S.C. .sctn. 371 National Phase
conversion of International (PCT) Patent Application No.
PCT/CN2018/114023, filed on Nov. 5, 2018. The contents of the
above-identified application are incorporated herein by reference.
The PCT International Patent Application was filed and published in
Chinese.
TECHNICAL FIELD
The present invention relates to the field of liquid crystal
display, and more particularly, to a driving method for a liquid
crystal display device.
BACKGROUND
Liquid crystal display (LCD) device has the advantages of being
good in image quality, small in size, light in weight, low in
driving voltage, low in power consumption, free of radiation, and
relatively low in manufacturing cost, and occupies domination in
the field of flat panel display.
Liquid crystal display devices are gradually developing towards a
wide viewing angle, for example, an in-plane switching mode (IPS)
or fringe field switching mode (FFS) liquid crystal display device
can achieve a wide viewing angle. However, people are currently
paying more and more attention to protecting their privacy, and
there are many things that they don't like to share with others. In
public, people always hope that the content is kept secret when
they are looking at their mobile phones or browsing computers.
Therefore, the display device with a single viewing angle mode can
no longer meet the needs of the user. In addition to the need for a
wide viewing angle, it is also desirable to be able to switch the
display device to a narrow viewing angle mode when anti-peeping is
required.
Currently, there is a way to use a viewing angle control electrode
on the color filter substrate (CF) to apply a vertical electric
field to liquid crystal molecules to achieve switching between wide
and narrow viewing angles. Referring to FIGS. 1 and 2, the liquid
crystal display device includes an upper substrate 11, a lower
substrate 12 and a liquid crystal layer 13 disposed between the
upper substrate 11 and the lower substrate 12. The upper substrate
11 is provided with a viewing angle control electrode 111. As shown
in FIG. 1, during wide viewing angle display, the viewing angle
control electrode 111 of the upper substrate 11 is not applied with
a voltage, so that the liquid crystal display device realizes wide
viewing angle display. As shown in FIG. 2, when a narrow viewing
angle display is required, the viewing angle control electrode 111
of the upper substrate 11 is applied with a voltage, the liquid
crystal molecules in the liquid crystal layer 13 will tilt due to
the vertical electric field E, and the liquid crystal display
device will leak light from large observation angles, so that a
narrow viewing angle is finally achieved.
That is, in the narrow viewing angle mode, by applying a bias
voltage on the viewing angle control electrode of the CF side, the
liquid crystal molecules are tilted to form light leakage from
large observation angles, so as to control the viewing angle of the
liquid crystal display device and realize the anti-peeping effect.
However, in the narrow viewing angle mode, there is a problem of
uneven display (i.e., mura) at large observation angles, which
affects the user experience.
SUMMARY
An object of the present invention is to provide a driving method
for a liquid crystal display device, which can avoid the problem of
uneven display at large observation angles of the liquid crystal
display device in a narrow viewing angle mode, to improve the user
experience.
An embodiment of the present invention provides a driving method
for a liquid crystal display device having a wide viewing angle
mode and a narrow viewing angle mode. The driving method
includes:
in the wide viewing angle mode, all frames of the liquid crystal
display device having the same display brightness;
in the narrow viewing angle mode, the odd frames and the even
frames of the liquid crystal display device having different
display brightness.
Further, in the narrow viewing angle mode, the display brightness
of the odd frames of the liquid crystal display device is higher
than that of the even frames, or the display brightness of the even
frames of the liquid crystal display device is higher than that of
the odd frames.
Further, in the narrow viewing angle mode, the liquid crystal
display device adopts a way of varying the driving voltages to
realize that the odd frames and the even frames have different
display brightness.
Further, in the narrow viewing angle mode, the liquid crystal
display device is driven with two sets of gamma voltages of
different voltage values, one set of gamma voltages is used when
the odd frames are displayed, and the other set of gamma voltages
is used when the even frames are displayed.
Further, in the narrow viewing angle mode, the liquid crystal
display device adopts a way of processing the image data to achieve
that the odd frames and the even frames have different display
brightness.
Further, the liquid crystal display device includes an image
processor, the image processor is used to add or subtract the image
data, and the processed image data is then transmitted to the
liquid crystal display device for display.
Further, the liquid crystal display device includes a first
substrate, a second substrate disposed opposite to the first
substrate, and a liquid crystal layer located between the first
substrate and the second substrate, an auxiliary electrode is
provided on the first substrate, a common electrode and pixel
electrodes are provided on the second substrate; wherein:
when a DC reference voltage is applied to the common electrode, and
the voltage applied to the auxiliary electrode is same or similar
as the common electrode, the voltage difference between the
auxiliary electrode and the common electrode is less than a preset
value, and the liquid crystal display device is in the wide viewing
angle mode;
when a DC reference voltage is applied to the common electrode, and
an AC voltage fluctuated up and down around the DC reference
voltage is applied to the auxiliary electrode, the voltage
difference between the auxiliary electrode and the common electrode
is greater than a preset value, and the liquid crystal display
device is in the narrow viewing angle mode.
Further, the liquid crystal display device includes a first
substrate, a second substrate disposed opposite to the first
substrate, and a liquid crystal layer located between the first
substrate and the second substrate, an auxiliary electrode is
provided on the first substrate, a common electrode and pixel
electrodes are provided on the second substrate; wherein:
when a DC reference voltage is applied to the auxiliary electrode,
and the voltage applied to the common electrode is same or similar
as the auxiliary electrode, the voltage difference between the
common electrode and the auxiliary electrode is less than a preset
value, and the liquid crystal display device is in the wide viewing
angle mode;
when a DC reference voltage is applied to the auxiliary electrode,
and an AC voltage fluctuated up and down around the DC reference
voltage is applied to the common electrode, the voltage difference
between the common electrode and the auxiliary electrode is greater
than a preset value, and the liquid crystal display device is in
the narrow viewing angle mode.
Further, the AC voltage changes its polarity once every two frames,
and the period of the AC voltage is four times the display time of
each frame of the liquid crystal display device.
Further, the AC voltage changes its polarity twice per frame, and
the period of the AC voltage is equal to the display time of each
frame of the liquid crystal display device.
Further, the common electrode and the pixel electrodes are located
on different layers and are separated by an insulating layer. The
pixel electrodes are located above the common electrode. Each pixel
electrode has a comb-shaped structure, and the common electrode is
a whole surface structure.
Further, in the narrow viewing angle mode, an image refresh rate of
the liquid crystal display device is 120 frames per second.
Further, the liquid crystal display device is provided with a
viewing angle switching button configured for users to switch
different viewing angle modes of the liquid crystal display
device.
Further, the liquid crystal display device is provided with a
detection sensor configured for detecting whether there is a person
near the liquid crystal display device, and the liquid crystal
display device is controlled to switch between different viewing
angle modes automatically according to the detection result.
Further, the liquid crystal display device detects the usage
scenarios of the users, and the liquid crystal display device is
controlled to switch between different viewing angle modes
automatically according to the detection result.
The driving method of the liquid crystal display device provided by
embodiments of the present invention, in the narrow viewing angle
mode, by using the driving method of bright frames and dark frames
alternating with each other, the image quality in the bias mode is
better than that of the original, the mura degree is significantly
slight, to improve the mura problem of the existing liquid crystal
display device at large observation angles in the bias mode,
thereby improving the smoothness of dynamic picture display and
improving the user experience.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram showing a cross-sectional structure
of a conventional liquid crystal display device in a wide viewing
angle mode.
FIG. 2 is a schematic diagram showing a cross-sectional structure
of the liquid crystal display device of FIG. 1 in a narrow viewing
angle mode.
FIG. 3 is a schematic circuit diagram of a liquid crystal display
device in an embodiment of the present invention.
FIG. 4 is a schematic diagram showing a cross-sectional structure
of the liquid crystal display device of FIG. 3 in a wide viewing
angle mode.
FIG. 5 is a schematic diagram showing a cross-sectional structure
of the liquid crystal display device of FIG. 3 in a narrow viewing
angle mode.
FIG. 6 is a flowchart of a driving method for the liquid crystal
display device of FIG. 3.
FIG. 7 is a schematic diagram of one driving waveform of the liquid
crystal display device of FIG. 3 in the narrow viewing angle
mode.
FIG. 8 is a schematic diagram of another driving waveform of the
liquid crystal display device of FIG. 3 in the narrow viewing angle
mode.
FIGS. 9a and 9b are schematic diagrams of other driving waveforms
of the liquid crystal display device of FIG. 3 in the narrow
viewing angle mode.
FIG. 10 is a block diagram showing a module structure of the liquid
crystal display device of FIG. 3.
FIGS. 11a and 11b are schematic plan views showing the planar
structure of the liquid crystal display device of FIG. 3 in one
example.
FIG. 12 is a schematic plan view showing the planar structure of
the liquid crystal display device of FIG. 3 in another example.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In order to make the objectives, technical solutions, and
advantages of the present invention clear, the embodiments of the
present invention will be further described below with reference to
the accompanying drawings.
Referring to FIGS. 3 to 5, an embodiment of the present invention
provides a liquid crystal display device that can switch between a
wide viewing angle (WVA) mode and a narrow viewing angle (NVA)
mode. The liquid crystal display device includes a first substrate
21, a second substrate 22 disposed opposite to the first substrate
21, and a liquid crystal layer 23 located between the first
substrate 21 and the second substrate 22. Specifically, the first
substrate 21 is, for example, a color filter substrate, and the
second substrate 22 is, for example, a thin film transistor array
substrate.
The first substrate 21 is provided with a color resist layer 212, a
black matrix 213, an overcoat layer 214, and an auxiliary electrode
215 on the side facing the liquid crystal layer 23. In this
embodiment, the color resist layer 212 and the black matrix 213 are
staggered and formed on the surface of the first substrate 21
facing the liquid crystal layer 23. The color resist layer 212
includes, for example, three color resist materials of red (R),
green (G), and blue (B). The overcoat layer 214 covers the color
resist layer 212 and the black matrix 213. The auxiliary electrode
215 is formed on the overcoat layer 214, and the auxiliary
electrode 215 may be a whole surface structure or a patterned
structure.
The second substrate 22 is provided with scan lines 222, data lines
223, thin film transistors (TFT) 224, a common electrode 225, an
insulating layer 226, and pixel electrodes 227 on the side facing
the liquid crystal layer 23. A plurality of scan lines 222 and a
plurality of data lines 223 are crossed each other to define a
plurality of pixel units P. Each pixel unit P is provided with a
pixel electrode 227, which is connected to a corresponding scan
line 222 and a corresponding data line 223 through a thin film
transistor 224. The common electrode 225 and the pixel electrodes
227 are spaced apart and insulated from each other by the
insulating layer 226, and the pixel electrodes 227 may be located
above or below the common electrode 225. In this embodiment, the
pixel electrodes 227 are located above the common electrode 225,
the common electrode 225 is a whole surface structure, and each
pixel electrode 227 has a comb-shaped structure, so that the liquid
crystal display device is formed into a fringe field switching
(FFS) mode to obtain a wide viewing angle in normal display.
In other embodiments, the common electrode 225 and the pixel
electrodes 227 may be located in the same layer and insulated from
each other. In this embodiment, the insulating layer 226 may be
omitted. The pixel electrode 227 has a comb-shaped structure, and
the common electrode 225 is formed into a comb-shaped structure at
a position corresponding to each pixel electrode 227 in order to
mutually insert with each other, so that the liquid crystal display
device is formed into an in-plane switching (IPS) mode, which can
also obtain a wide viewing angle during normal display.
It should be understood that in this embodiment, only the film
layers related to the present invention are illustrated on the
first substrate 21 and the second substrate 22, and the unrelated
film layers are omitted.
In this embodiment, the liquid crystal layer 23 adopts positive
liquid crystal molecules, that is, the liquid crystal molecules
with positive dielectric anisotropy. In the initial state (i.e., no
voltage is applied to the liquid crystal display device), the
positive liquid crystal molecules in the liquid crystal layer 23
assume a lying posture which is substantially parallel to the first
substrate 21 and the second substrate 22, and the length direction
of the positive liquid crystal molecules is substantially parallel
to the surface of the first substrate 21 and the second substrate
22 (as shown in FIG. 4). In practical applications, the positive
liquid crystal molecules within the liquid crystal layer 23 may
have small initial pretilt angle relative to the first substrate 21
and the second substrate 22, and a range of the initial pretilt
angle may be less than or equal to 10 degrees, i.e.,
0.degree..ltoreq..theta..ltoreq.10.degree..
Referring to FIGS. 4 and 5, by applying different voltages on the
auxiliary electrode 215 and the common electrode 225, the liquid
crystal display device can be controlled to switch between a wide
viewing angle mode and a narrow viewing angle mode.
For example, when a DC reference voltage Vref is applied to the
common electrode 225, and the voltage applied to the auxiliary
electrode 215 is same or similar as the common electrode 225, the
voltage difference between the auxiliary electrode 215 and the
common electrode 225 is less than a preset value (e.g., less than
1V), the tilt angle of the liquid crystal molecules in the liquid
crystal layer 23 nearly does not change and the liquid crystal
molecules remain in a substantially lying posture, so the liquid
crystal display device is in a normal wide viewing angle mode (as
shown in FIG. 4). When a DC reference voltage Vref is applied to
the common electrode 225 and an AC voltage Vac fluctuated up and
down around the DC reference voltage Vref is applied to the
auxiliary electrode 215, the voltage difference between the
auxiliary electrode 215 and the common electrode 225 is greater
than a preset value (e.g., greater than 3V), a strong vertical
electric field E will be generated between the first substrate 21
and the second substrate 22 in the liquid crystal cell, causing the
liquid crystal molecules to deflect, and the tilt angle of the
liquid crystal molecules relative to the first substrate 21 and the
second substrate 22 increases and the liquid crystal molecules are
tilted and changed from the lying posture to a tilted posture,
causing the liquid crystal display device to occur light leakage at
large observation angles, such that the liquid crystal display
device finally enters a narrow viewing angle mode (as shown in FIG.
5).
Alternatively, when a DC reference voltage Vref is applied to the
auxiliary electrode 215, and the voltage applied to the common
electrode 225 is same or similar as the auxiliary electrode 215,
the voltage difference between the common electrode 225 and the
auxiliary electrode 215 is less than a preset value (e.g., less
than 1V), the tilt angle of the liquid crystal molecules in the
liquid crystal layer 23 nearly does not change and the liquid
crystal molecules remain in a substantially lying posture, so the
liquid crystal display device is in a normal wide viewing angle
mode (as shown in FIG. 4). When a DC reference voltage Vref is
applied to the auxiliary electrode 215 and an AC voltage Vac
fluctuated up and down around the DC reference voltage Vref is
applied to the common electrode 225, the voltage difference between
the common electrode 225 and the auxiliary electrode 215 is greater
than a preset value (e.g., greater than 3V), a strong vertical
electric field E will be generated between the first substrate 21
and the second substrate 22 in the liquid crystal cell, and the
liquid crystal molecules will tilt under the action of the vertical
electric field E, so that the tilt angle of the liquid crystal
molecules relative to the first substrate 21 and the second
substrate 22 increases and the liquid crystal molecules are tilted
and changed from the lying posture to a tilted posture, causing the
liquid crystal display device to occur light leakage at large
observation angles, such that the liquid crystal display device
finally enters a narrow viewing angle mode (as shown in FIG.
5).
As shown in FIGS. 4-5, in order to apply a voltage signal to the
auxiliary electrode 215 on the first substrate 21, the first
substrate 21 can be conducted to the second substrate 22 through a
conductive adhesive 80 in the non-display area around the liquid
crystal display device, so that a driving circuit 60 provides a
voltage signal to the second substrate 22, and then the second
substrate 22 applies the voltage signal to the auxiliary electrode
215 of the first substrate 21 through the conductive adhesive
80.
In the wide viewing angle mode, the voltage difference between the
auxiliary electrode 215 and the common electrode 225 may be in the
range of from 0V to 1V. Preferably, the same voltage is applied to
both the auxiliary electrode 215 and the common electrode 225, so
that the voltage difference between the auxiliary electrode 215 and
the common electrode 225 is zero, and a better wide viewing angle
display effect can be achieved.
In the narrow viewing angle mode, the voltage difference between
the auxiliary electrode 215 and the common electrode 225 may be in
the range of from 3V to 7V. For example, the voltage difference
between the auxiliary electrode 215 and the common electrode 225
can be selected as 4V, 5V, 6V, etc. as needed to achieve the
desired narrow viewing angle display effect.
Referring to FIG. 6, an embodiment of the present invention further
provides a driving method for the liquid crystal display device.
The liquid crystal display device has a wide viewing angle mode and
a narrow viewing angle mode. The liquid crystal display device can
determine the required viewing angle mode according to a viewing
angle switching signal HVA which may be issued by the users or
automatically generated by the liquid crystal display device.
Specifically, the viewing angle switching signal HVA may be a
voltage signal, and the liquid crystal display device may determine
the required viewing angle mode according to the level of the
viewing angle switching signal HVA. For example, when the viewing
angle switching signal HVA is at a high level, the liquid crystal
display device is switched to the narrow viewing angle mode; when
the viewing angle switching signal HVA is at a low level, the
liquid crystal display device is switched to the wide viewing angle
mode.
As described above, when a DC reference voltage Vref is applied to
one of the auxiliary electrode 215 and the common electrode 225 and
a voltage that is the same as or close to the DC reference voltage
Vref is applied to the other one of the auxiliary electrode 215 and
the common electrode 225, the liquid crystal display device is in
the wide viewing angle mode. When a DC reference voltage Vref is
applied to one of the auxiliary electrode 215 and the common
electrode 225 and an AC voltage Vac fluctuated up and down around
the DC reference voltage Vref is applied to the other one of the
auxiliary electrode 215 and the common electrode 225, the liquid
crystal display device is in the narrow viewing angle mode.
Specifically, in the wide viewing angle mode, all the frames of the
liquid crystal display device have the same display brightness; but
in the narrow viewing angle mode, the odd frames and the even
frames of the liquid crystal display device have different display
brightness.
Specifically, in the narrow viewing angle mode, the odd frames and
the even frames of the liquid crystal display device have different
display brightness, either the display brightness of the odd frames
of the liquid crystal display device is higher than that of the
even frames or the display brightness of the even frames of the
liquid crystal display device is higher than that of the odd
frames.
In the narrow viewing angle mode, in order to make the odd frames
and the even frames of the liquid crystal display device have
different display brightness, it can be achieved by varying the
driving voltages in the odd frames and the even frames, because the
display brightness of the liquid crystal display device is related
to the driving voltages Vpixel applied to the data lines 223.
Specifically, a way of varying the driving voltages may be any one
of the following a1-a6:
a1: in the odd frames, the driving voltages Vpixel on the data
lines 223 are increased so that the odd frames become bright
frames; while in the even frames, the driving voltages Vpixel on
the data lines 223 are reduced so that the even frames become dark
frames.
a2: in the even frames, the driving voltages Vpixel on the data
lines 223 are increased so that the even frames become bright
frames; while in the odd frames, the driving voltages Vpixel on the
data lines 223 are reduced so that the odd frames become dark
frames.
a3: in the odd frames, the driving voltages Vpixel on the data
lines 223 are increased so that the odd frames become bright
frames; but in the even frames, the original driving voltages
Vpixel are maintained on the data lines 223 so that the even frames
become dark frames.
a4: in the even frames, the driving voltages Vpixel on the data
lines 223 are increased so that the even frames become bright
frames; but in the odd frames, the original driving voltages Vpixel
are maintained on the data lines 223 so that the odd frames become
dark frames.
a5: in the odd frames, the driving voltages Vpixel on the data
lines 223 are reduced so that the odd frames become dark frames;
but in the even frames, the original driving voltages Vpixel are
maintained on the data lines 223 so that the even frames become
bright frames.
a6: in the even frames, the driving voltages Vpixel on the data
lines 223 are reduced so that the even frames become dark frames;
but in the odd frames, the original driving voltages Vpixel are
maintained on the data lines 223 so that the odd frames become
bright frames.
FIG. 7 is a schematic diagram depicting one kind of driving
waveform of the liquid crystal display device when displaying a
L255 gray-scale static image. Referring to FIG. 7, in the narrow
viewing angle mode, it is assumed that the image refresh rate
(i.e., frame rate) of the liquid crystal display device is 120
frames per second, wherein high driving voltages are applied to the
data lines 223 in the sixty odd frames which are correspondingly
displayed as high brightness, while low driving voltages are
applied to the data lines 223 in the sixty even frames which are
correspondingly displayed as low brightness. That is, when the same
gray scale (e.g., L255 gray scale) is displayed, the driving
voltages applied to the data lines 223 in the odd frames are higher
than the driving voltages applied to the data lines 223 in the even
frames, so that the brightness of the odd frames is greater than
the brightness of the even frames. As shown in FIG. 7, Frame N and
Frame N+2 are bright frames, while Frame N+1 and Frame N+3 are dark
frames.
FIG. 7 only takes the display of L255 gray scale as an example, but
in fact, the driving voltages of the bright frames and dark frames
corresponding to different gray scales can be defined according to
two sets of different gray scale-voltage curves (L-V curves). That
is, in the narrow viewing angle mode, the liquid crystal display
device can be driven by two sets of gamma voltages with different
voltage values, one set of gamma voltages (e.g., Gamma1) is used
when displaying the odd frames, and another set of gamma voltages
(e.g., Gamma2) is used when displaying the even frames. When the
voltage value of Gamma1 is greater than the voltage value of
Gamma2, the odd frames can be bright frames and the even frames can
be dark frames. When the voltage value of Gamma1 is less than the
voltage value of Gamma2, the odd frames can be dark frames and the
even frames can be bright frames.
Specifically, a resistor string or a gamma chip may be used to
generate different sets of required gamma voltages, namely the
above-mentioned Gamma1 and Gamma2.
As shown in FIG. 7, in the narrow viewing angle mode, the AC
voltage Vac applied to the auxiliary electrode 215 or the common
electrode 225 may change its polarity once every two frames. At
this time, the period T2 of the AC voltage Vac is four times the
display time T1 of each frame of the liquid crystal display
device.
As shown in FIG. 8, in the narrow viewing angle mode, the AC
voltage Vac applied to the auxiliary electrode 215 or the common
electrode 225 may also change its polarity twice per frame. At this
time, the period T2 of the AC voltage Vac is equal to the display
time T1 of each frame of the liquid crystal display device.
In FIGS. 7 and 8, it is shown that the waveform of the AC voltage
Vac is a square wave. Unlike FIG. 8, FIGS. 9a and 9b show that the
waveform of the AC voltage Vac is a triangular wave or a sine
wave.
Optionally, in the narrow viewing angle mode, in order to make the
odd frames and the even frames of the liquid crystal display device
have different display brightness, it can also be realized by
processing the image data (i.e., the data to be displayed).
Referring to FIG. 10, the liquid crystal display device further
includes an image processor 31, a display controller 32, and a
source driver 33. The image processor 31 can be used to add or
subtract the image data, and the processed image data is
transmitted to the source driver 33 by the display controller 32,
and then transmitted to the liquid crystal display device (LCD) by
the source driver 33 through each data line 223 for display.
For example, assuming that the original display gray level
corresponding to the image data is Ln (Ln is any gray level from L0
to L255), when the image data is subjected to an adding process,
the display gray level corresponding to the image data may be
L(n+1), which is equivalent to increasing its display gray level to
improve the display brightness; when the image data is subjected to
a subtracting process, the display gray level corresponding to the
image data may be L(n-1), which is equivalent to reducing its
display gray scale to reduce the display brightness. That is,
adding the image data values can increase the display brightness,
and subtracting the image data values can reduce the display
brightness. Thus, the ways of processing the image data can be any
one of the following b1-b6:
b1: the image data values of the odd frames are added so that the
odd frames become bright frames; the image data values of the even
frames are subtracted so that the even frames become dark
frames.
b2: the image data values of the even frames are added so that the
even frames become bright frames; the image data values of the odd
frames are subtracted so that the odd frames become dark
frames.
b3: the image data values of the odd frames are subtracted so that
the odd frames become bright frames; but the image data values of
the even frames are unchanged so that the even frames become dark
frames.
b4: the image data values of the even frames are added so that the
even frames become bright frames; but the image data values of the
odd frames are unchanged so that the odd frames become dark
frames.
b5: the image data values of the odd frames are subtracted so that
the odd frames become dark frames; but the image data values of the
even frames are unchanged so that the even frames become bright
frames.
b6: the image data values of the even frames are subtracted so that
the even frames become dark frames; but the image data values of
the odd frames are unchanged so that the odd frames become bright
frames.
Referring to FIG. 11a to FIG. 11b, the liquid crystal display
device may be provided with a viewing angle switching button 50 for
switching different viewing angle modes of the liquid crystal
display device. The viewing angle switching button 50 may be a
mechanical button (as shown in FIG. 11a) or a virtual button (as
shown in FIG. 11b, set through a window). When a user needs to
switch between the wide and narrow viewing angle modes, a viewing
angle switching signal HVA can be sent to the liquid crystal
display device by operating the viewing angle switching button 50,
and finally the driving circuit 60 controls the voltages applied to
the auxiliary electrode 215 and the common electrode 225 to achieve
the switching between the wide and narrow viewing angle modes.
Therefore, by operating the viewing angle switching button 50, the
user can switch between the wide viewing angle mode and the narrow
viewing angle mode easily with good operation flexibility and
convenience.
Referring to FIG. 12, in another embodiment, the liquid crystal
display device may be provided with a detection sensor 90, and the
detection sensor 90 is used to detect whether there is a person
near the liquid crystal display device. The number of the detection
sensor 90 may be multiple, distributed on the outer casing of the
liquid crystal display device. The detection sensor 90 may be an
infrared sensor. The controller of the liquid crystal display
device can control the liquid crystal display device to switch
between the wide and narrow viewing angle modes automatically,
according to a detection result of the detection sensor 90. For
example, when the detection sensor 90 detects that somebody is near
the liquid crystal display device, the liquid crystal display
device is controlled to switch to the narrow viewing angle mode
automatically; when the detection sensor 90 detects that nobody is
near the liquid crystal display device, the liquid crystal display
device is controlled to switch to the wide viewing angle mode
automatically. Therefore, by providing the detection sensor 90, the
wide and narrow viewing angle modes can be switched automatically,
without requiring the user to switch the wide and narrow viewing
angle modes manually, thereby further improving the user
experience.
In other embodiments, the liquid crystal display device can also be
controlled to switch between wide and narrow viewing angle modes
automatically, according to the user's usage scenarios. For
example, when it is detected that the user is using an e-mail or
inputting a password, and other usage scenarios that require
anti-peeping, the liquid crystal display device is controlled to
switch to the narrow viewing angle mode automatically; when the
user is not in these usage scenarios that require anti-peeping, the
liquid crystal display device is controlled to switch to the wide
viewing angle mode automatically.
The embodiments of the present invention provide driving methods of
a liquid crystal display device, in the narrow viewing angle mode,
by alternately driving bright and dark frames, the display quality
of the images in the bias mode is better than that of the original
images, and the degree of mura is obviously reduced, to improve the
large observation angle mura problem of the existing liquid crystal
display device in the bias mode and improve the smoothness of the
dynamic picture display, thereby improving the user experience.
The liquid crystal display device provided by the embodiments of
the present invention can easily switch between the wide viewing
angle mode and the narrow viewing angle mode under different
occasions, has good operation flexibility and convenience, to
achieve a multifunctional liquid crystal display device integrated
with the functions of entertainment and privacy protection.
The above are only the preferred embodiments of the present
invention and are not intended to limit the present invention. Any
modification, equivalent replacement, improvement, etc. within the
spirit and principle of the present invention should be included in
the protection scope of the present invention.
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